Copy of 1958, Lituya Bay Mega-Tsunami

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Transcript of Copy of 1958, Lituya Bay Mega-Tsunami

Lituya BayMega-Tsunami The Lituya Bay The Earthquake In July 9, 1958, a large earthquake along the Fairweather Fault struck Southeastern Alaska which triggered a landslide that caused 30 million cubic meters of rock and ice to fall into the narrow inlet of Lituya Bay. The magnitude of the earthquake was about 8.3, although some sources say it was a 7.9, on the Richter Scale. The Mega-Tsunami After the enormous landslide, giant waves were created. Then into a mega-tsunami which rose to a maximum height of 524 meters at the head of Lituya Bay. Which was 143 meters taller than the Empire State. Welcome to our group's presentation First of all, let us introduce you to our group members Kandit Kasiwat #18 M.39 Tanatip Judyai #21 M.39 Sarut Chonateethon #28 M.39 The Lituya Bay is a T-shaped fjord on the Fairweahter Fault in the northeastern side of the Gulf of Alaska. It has a width of 3 kilometers, a length of 11 kilometers and a depth of 220 meters. The two ways that connect to the T-shaped bay are the Gilbert and Crillon inlets. This is the highest recorded mega-tsunami and the largest known in modern times. Environmental Effects Property Damage and Death The Destruction The wave spread across the Gilbert Inlet and the rest of the Lituya Bay wiping everything in its path on either side, over an area of about 10.4 square kilometers. There could be other factors that may have created into mega-tsunami including tectonic movements along with the earthquake, collapse of a glacier, sudden drainage of the lake on the Lituya Glacier and major rockfall that occurred on Gilbert Inlet. The mega-tsunami washed away the trees, grass, and soil down to the bedrock. On the time the tsunami occurred, there were three boats on the bay. Two of them were pushed by the waves to the mountainsides, but one sank. The wave then reached the Khantaak Island and killed 3 people. In Yakutat, some infrastructures such as bridges, docks and oil lines were damaged. A water tower collapsed and a cabin was highly damaged. Sand boils and fissures occurred near the coast southeast, and cut out underwater Alaskan Communication System cables. There were also lighter damage reported in Pelican and Sitka. Witness At the time, there were three fishing boats anchored near the entrance of the bay. One of these boats sunk and the two people on board lost their lives. The other two boats were able to ride the wave. Among the survivors were William A. Swanson and Howard G. Ulrich, who provided infos of their observations.Miller (1960) documented in great detail all accounts, measurements, and observations related to the giant waves in Lituya Bay in a report published by the U.S. Geological Survey. Captain Elliot B. Roberts, of what was then the U.S. Coast and Geodetic Survey, created extensive photogrammetric surveys and provided a good account of the event in the Smithsonian Institution Annual Report for 1960. How did they know? To measure the height of the biggest wave, all scientists had to look for the high water mark, the line where the water reached its highest point on the nearby land. It can be found on the uppermost edge of the damaged area. Then, they measured the elevation of the highest point on the high water mark to get a measurement of 524meters high, the biggest wave ever measured. Developments and Preparations After the intensive event, Los Alamos National Laboratory developed a simulation model which can be used for better estimations and predictions. Much can be learnt from that. It could also lead to a better understatement of the disaster and it could be observed to prepare for any possible future events that would give us better advantages for developing the best possible way of preventing major damages and limit the damages. Tectonic setting of the region Setting of the area is controlled by the interaction of the Pacific and North American plates. The great plates caused by the earthquake that affected to boundaries countries to the South, near the California and through the San Andrea which boundary to Maine. The damage that cause people and places in Lituya

Aerial photograph of Lituya Bay from the front taken from an aircraft flying at 3,000 feet. Damage from the 1958 megatsunami can be seen in this picture as the lighter colored areas on the sides of the bay, where the trees were stripped by the waves resulting from the megatsunami. The greatest disaster whichmake an earthquake and tsunami